1. Field of the Invention
The present invention relates to a movement sensor and to the use thereof for position and movement detection.
2. Discussion of Background Information
Movement sensors have been known for decades. They primarily serve the purpose of detecting simple movements. They exist in different variants, with all of them having in common the fact that they contain a conductive ball or a drop of mercury. Such apparatuses are known e.g. from U.S. Pat. No. 3,927,286 and U.S. Pat. No. 4,434,337.
U.S. Pat. No. 5,410,113 A discloses a movement sensor comprising a plurality of plate-type layers on which individual sensors are arranged. The cover plate and the base plate each have a sensor-associated surface, which are connected to connection contacts via conductor tracks. A chamber plate having a cutout is arranged between the cover plate and the base plate. The sensor-associated surfaces of the cover plate and of the base plate are arranged with register accuracy over the openings of the cutout of the chamber plate. This gives rise to a hollow chamber, the inner surfaces of which are electrically conductive. An electrically conductive ball is arranged in the hollow chamber.
EP 1 939 911 furthermore discloses a vibration sensor in which, in a manner similar to that in the case of U.S. Pat. No. 5,410,113, a movement sensor is constructed from a plurality of plates comprising cover, chamber plate and base plate. A ball is situated in the hollow chamber formed by the stacking of the plates, the hollow chamber being electrically conductive at its inner surfaces.
What is disadvantageous about the systems described is that a multiplicity of contact columns arise when a plurality of individual sensors are used. This has considerable disadvantages in terms of production engineering and costs. It is furthermore disadvantageous that a fast and parallel functional test of the individual sensors is not possible in the case of the sensors described.
DE 10 158 416 C1 and WO 002008071289 A1 disclose movement sensors of plate design which react on account of a mechanical excitation with a change in resistance at the outer connections. The movement sensor described in DE 10 158 416 C1 is constructed from three plates. A base plate and top plate enclose a chamber plate, which has a hole centrally. This gives rise to a cavity, in which a ball is arranged. The cover, just like the base, can have an inner sensor-associated surface, a cover contact pad. The relevant construction technology does not allow detection of the position in which the switch is situated with the gravitational field.
DE 10 158 416 C1 alternatively describes a construction in which the sensor has three sensor-associated surfaces. In this configuration, cover and base contact pads are led parallel to the outer contact pad. Consequently, only movement detection independent of the position is possible, to be precise independently of whether the sensor leans with the cover or with the base toward the ground. Accordingly, it is not possible to differentiate whether the change in resistance of the sensor is caused on account of the conduct between ball, cavity and cover or between ball, cavity and base side.
The sensor in accordance with DE 10 158 416 C1 reacts extremely sensitively to small accelerations and changes its status upon the tiniest of vibrations. A more slowly acting sensor behavior is required, however, in a large number of applications. This holds true particularly in the cases in which electronic devices are intended to be activated only when they are moved to a great extent. In many cases, the intention is also to avoid a situation in which even in the event of a slight vibration within a building, for example triggered by a truck travelling past, devices in a power-saving mode are activated unnecessarily on account of the sensor pulse and thus have an increased power consumption.
What is disadvantageous in the case of DE 10 158 416 C1 and also in the case of WO 00200807128789 A1 is also the fact that a depression is produced in the sensor-associated base surface by means of a drilling process and subsequent production of an electrically conductive sleeve by electrolytic process technologies. This gives rise to a burr in the metallic layer at the drilled edge, which burr can be reduced only by complex mechanical processing steps such as brushing, grinding or lapping. On account of the burr, an excessively elevated location can arise around the depression, the properties of which are disadvantageous. This is because, owing to the hollow wall, the ball will not, or not reproducibly, attain the desired rest position. In WO 002008071289 A1, a stable rest position is not actually desired. This is because the device is designed, rather, for realizing the highest possible sensitivity of the sensor. Therefore, it is not the aim of this invention to produce an increased and adjustable response threshold and a defined rest position.
Accordingly, it is an object of the present invention to provide a movement sensor which no longer has the disadvantages described. The aim of the invention is, inter alia, to provide a movement sensor in which the response threshold of the sensitivity of micro, movement and bearing sensors can be set in wide ranges and, in particular, can be increased. Secondly, what is intended to be achieved is that the ball in the sensor lies in a defined rest position.